Mucus hypersecretion in airways is a common pathological
change observed in chronic inflammatory diseases and asthma. We investigated
the new role of cell attachment to the extracellular matrix (ECM) on the
production of the airway mucus protein, MUC5AC mucin, in human airway
epithelial cells, NCI-H292. MUC5AC levels of cells cultured on low adhesion
plates were 10-fold higher than those of cells cultured on adhesion plates.
Cells cultured on bovine serum albumin (BSA) coated plates, which produce low adhesion conditions, also induced the up-regulation of MUC5AC. Mucin staining by
PAS and MUC5AC immunodetection confirmed that mucin proteins were overproduced
under low adhesion conditions. The major adhesion molecule between cells and
the ECM was integrins. A time-course experiment showed that the expression
patterns of integrin β1 and MUC5AC
protein were inversely proportional. The inhibition of integrin β1 induced an increase in MUC5AC production in cells cultured under adhesion conditions, but not under low adhesion
conditions. These results suggested that cell attachment regulates MUC5AC production, which is up-regulated by low adhesion to the ECM, and MUC5AC
production is inversely proportional to the function of integrin β1.